Compounds related to nucleosides: isonucleosides, "stretched-out" nucleosides, and "abbreviated" dinucleosides will be made, tested for anti-viral and oncogenic activity, and converted to coenzyme and cofactor analogs to determine the requirements for hydrogen-bonding and for the geometry of their interaction with specific enzymes. We will also synthesize and examine the spectra of a series of models for protein-nucleic acid interactions by linkage of indole and purine or pyrimidine moieties through a trimethylene bridge or through the 1' and 5' positions of ribose. We will continue our work on the identification of the cytokinin- active nucleosides adjacent to the anticodon site in specific transfer ribonucleic acids from bacterial, mold, plant, and animal sources. In an exploration of the question of cell division and differentiation processes, we will determine what modified ribonucleosides appear in tRNA, and how they are incorporated, when the applied cytokinin is unnatural and when it is natural. We will continue trying to improve on our anti-cytokinins, compounds which interfere with bacterial growth and other cell division processes. Finally, we will develop fluorescent, base-specific, site-specific reactions and reagents for probing tRNA, viral RNA, and other RNA structures and for effecting specific modifications including mutations.